Field of the Invention
The present invention relates to a cooling apparatus of a bus, and more particularly, to a cooling system for a bus which includes a cooling device (heat dissipating plate or an assembly of a heat dissipating plate and heat dissipating fan) mounted on a roof panel of the top of a bus and changed in inclination angle in accordance with the driving state of the vehicle and the temperature of fluid to be cooled, in order to additionally ensure a space for the engine room and more increase cooling performance and aerodynamic performance.
Description of Related Art
Large buses are usually driven in an RR (Rear engine Rear drive) type to be able to reduce the height from the ground and relatively increase the interior so that passengers can more easily get on the buses. The RR type buses have a relatively small output loss due to a short distance between the driving shaft and the engine and are easily repaired, so most of large buses are manufactured in the RR type.
In the RR type buses, a cooling system for cooling the coolant that cools the engine, oil for lubrication which circulates through the engine and the transmission, and air to flow into the engine is mounted around the engine placed at the rear portion of the buses. A pump, an intercooler, an oil pump, and a heat dissipating fan that make the coolant flow are connected to the engine by a belt or a chain to receive torque.
However, when the specifications of the cooling system are changed with a change in the engine specifications, it might be limited to mount the cooling system in the engine room due to more strict rules on the exhaust gas. Further, an increase in size of the cooling system with an increase in performance of the engine is disadvantageous in terms of using parts in common.
Accordingly, the applicant has filed Korean Patent Application No. 10-2013-0052805, titled “cooling system mounting structure of bus”, on May 10, 2013 in order to solve those problems. The cooling system disclosed in Korean Patent Application No. 10-2013-0052805 is composed of a heat dissipating plate and a heat dissipating fan and is mounted on the roof panel of a bus, cooling (coolant, oil, and intake air) with external air.
That is, as shown in FIG. 1, (in the structure disclosed in Korean Patent Application No. 10-2013-0052805) a cooling system 1 is disposed on the roof panel 101 of a bus 100 with the rear lifted up at a predetermined height than the front so that the heat dissipating plate is cooled by wind. The heat dissipating plate is provided so that coolant heated through an engine 2, intake air compressed and heated through an intercooler, or transmission oil or engine oil heated by the operation of the engine are cooled through it, and a heat dissipating fan is additionally mounted ahead of or behind the heat dissipating plate to improve the cooling performance.
In the structure, it was possible to increase spatial usability of the engine room by changing the position of the cooling system, and it was possible to improve the cooling performance because the heat dissipating plate is brought in direct contact with wind.
However, in this structure, it is possible to increase the cooling performance (with an increase in the inclination angle between the cooling system and the roof panel), but the air resistance is proportionally increased, so that the fuel efficiency is bad (the larger the inclination angle, the more the aerodynamic performance decreases). The air resistance should be improved because it increases in proportion to the vehicle speed.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.